I sometimes experienced kundulini years ago when I did TM but nothing earth-shattering. I experienced a heck of a lot of it years later in the Ramtha School, which targets kundulini raising as one of its goals. The first time I had a kundulini experience was in Avoriaz, France on an ATR. I didn't even know what it was. I had been meditating just four years, and on that course I fell in love. Every time I meditated, I felt love for that man, and I would experience this soft strong rush of energy, like a river of cloud, up both sides of the inside of my neck, and inside my ears, flowing into my head. It made a a gentle steady whoosh sound, like the ocean.
Ever since, when I feel great love, I feel that. When I started experimenting with intentional kundulini-raising in the Ramtha school, I realized it was the same as the powerful love experience. Of course kundulini can be much more intense, even really uncomfortable, and it has been for me sometimes. I know some people have found it painful and particularly distressing. I disagree with what some posters have written here, that kundulini is just a clearing of blockages in the physical nervous system and not important to full enlightenment. I think the uncomfortableness comes when the "river" encounters an obstacle, but I don't think the river itself is a blockage. To me that wouldn't make much sense. In the Ramtha school, people were taught to image a volcano in their first chakra ("first seal" in Ramtha terms). Then we'd do a forced sharp breath while envisioning pushing the volcano's energy up. We would play with that image -- erupting the volcano -- while blasting kundulini breaths to push the volcanic stream higher and higher up the spine. Kind of like those things at the fair where you bang the thing and the ball goes higher and higher, with the goal being to ding the bell at the top. We were told to envision the energy going all the way to the top of the head every time we blew. Everyone got very high on this, as it made the energy climb higher each time you did it. It was very empowering and enlivening. After a 40-minute session like this, we'd do exercises to develop our psychic abilities. I never used to be psychic before the Ramtha school, and I'm a lot more that way now. Plus it really enlivened my energy. I know it made me a lot smarter, I think because of the energy going into the head. I got a lot of good stuff out of that school and sometimes still practice the technique.